A Vicious Cycle is an episode of Happy Tree Friends, the fifth episode of Internet Season 4, and the 83rd episode overall.
Cub is riding a green metal tricycle in front of his house when the camera dramatically zooms in to the bushes, where the scene quickly changes to night and Fliqpy, covered in scratches, pops out from the bush. A police siren attracts his attention and he turns to see policemen Lumpy and Disco Bear emerge from the police car, wanting to arrest him.
Fliqpy pushes Cub off the tricycle and holds it over his head as an attempt to use it as a weapon. However, before he could do anything, a bolt of lightning strikes the tricycle and instantly reduces Fliqpy to a pile of ashes, which is then blown away by the breeze, leaving the tricycle intact. Cub, Disco Bear, and Lumpy stare intently at Cub's tricycle when Pop suddenly bursts into the scene, carrying a bowl of nachos and several bottles of beer, and he invites the officers in for a snack.
As Pop and the policemen are eating in the living room and watching TV, Cub happily rides his tricycle inside the house. However, Pop doesn't approve of Cub riding the trike indoors, so he proceeds to place it back outside, much to Pop's standards and Cub's disappointment. Back inside, as Pop tells Cub not to do such a thing again, the power suddenly goes out. A tricycle bell rings, the light on the bicycle turns on, and it jumps towards Disco Bear, making him scream. Lumpy quickly turns on a flashlight, and is shocked to discover blood and skidmarks on the couch. He becomes even more shocked to discover Disco Bear's severed head on the coffee table, with his brain exposed, and nachos embedded all over. As Pop leaves the scene, Lumpy closely examines the severed head.
Pop goes into the basement, and discovers the power box has been tampered with. The cover is blown open, and the switch is down. Pop proceeds to switch the power back on, and everything is normal. Happy and content, Pop climbs up the stairs to exit the basement, however, at the top of the steps, the tricycle stands there. The trike lightly taps on Pop, making him lose his balance. Pop eventually falls down the basement steps, which breaks an arm and a leg, and eventually into the control box, electrocuting him until his head pops off from his body.
Inside the living room, Lumpy is enjoying the blood-covered nachos inside Disco Bear's disembodied head, when all of a sudden the lights turn off again. Lumpy turns on his flashlight once more and sees the tricycle with Pop's severed head on the seat, the bell still ringing. Lumpy, still clutching Disco Bear's head full of chips, runs into the hallway closet to hide. The tricycle slowly rolls by the closet, oblivious to the fact that Lumpy is inside. However, Lumpy blows his cover by making a loud crunching noise as he devours another chip. The tricycle skids to a stop, opens the closet door, and attempts to tackle Lumpy, but Lumpy tries to fight back by holding the pedals. Unfortunately for the moose, the tricycle spins around and hits Lumpy's face five times, decapitating and killing him.
Sometime later, in the blood-covered living room, Cub contently rides the trike indoors once again. Just before the episode ends, Cub rings the trike's bell, which is stuffed in an eyeball.
"A wheel that turns gathers no rust."
- Fliqpy is struck by lightning and burns to dust, though his spirit continues to live in the tricycle.
- Disco Bear is shredded and decapitated by the tricycle. (Death not seen)
- Pop is knocked down the stairs by the tricycle and is electrocuted. He is decapitated soon after this.
- Half of Lumpy's head is torn off after the tricycle uses its rear wheels to hit him in the face multiple times.
- Prior to the episode, Fliqpy gets bruised and scratched (probably from a victim or the policemen).
- Cub is pushed off his tricycle by Fliqpy.
- Pop breaks an arm and a leg while falling down the basement stairs.
- Amount of surviving main characters: 2
- Amount of dead main characters: 3
- Total rate: 40%
- Pop's hat is slightly ripped and blackened when his head is on the tricycle.
- The description for the teaser misspells "Look" as "Ook".
- Cub was able to ride the tricycle without touching the pedals, even before Flippy possessed it.
- The design of Flippy's beret changes three times.
- When Disco Bear steps out of the car, he is shown much taller than he is supposed to be.
- When Fliqpy looks at Cub, Cub rings the bell on his trike, without moving either of his hands.
- Cub, Disco Bear, Lumpy and the police car are nowhere to be seen when the lightning strikes Fliqpy.
- Upon close observation, Fliqpy is already burnt to ashes before the lightning strikes him.
- Lumpy's antlers change places a few times.
- It makes no sense for Cub's eyes to turn white when the lights where turned off.
- Cub's safety pin changes position only one time and it's when he looks at Disco Bear's head.
- When Pop is pushed down the stairs, his hat doesn't fall off his head.
- Pop shouldn't have even been electrocuted, his body would have simply punctured the switch and he'd be stuck.
- Pop should have died from electrocution, not decapitation.
- The blood from Pop's head doesn't stain the tricycle seat.
- Lumpy shouldn't have been able to fall backwards in the closet.
- It's unknown how Disco Bear's head ended up on the couch at the end since Lumpy dropped it in the closet.